Compressed air efficiency

What is in this article?:

Carefully engineered responses to compressed-air demand will result in more efficient systems and savings in operating costs.

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Three concepts to remember

Several years later, I had the opportunity to work in the field for a major pneumatic tool-and-hoist manufacturer, which provided the next steps in my thinking process. During nine weeks of training, we were taught how to optimize air tools as they were applied to industrial applications. Three major ideas came from this.

One was that equipment efficiency was a function of how it was installed. Whenever we demonstrated or tried a tool for a user, we always tried to use our own company-supplied hose and fittings. There was no explanation or technology supplied, other than the fact that the tool would work better. It would achieve more torque, grind more metal, etc. We found that most manufacturers did not go out of their way to specifically state required volumes or pressures required for proper operation.

The second idea was that you could get applications to work more efficiently at the same pressure or get the same efficiency with more volume at less pressure. As the volume of air required by the tool was a function of the supply pressure, the higher the supply pressure, the more scfm exhausted. You can achieve the same amount of work energy by increasing the mass inversely proportionate to the reduction of the absolute pressure.

The third idea was that sometimes, because of compressed air supply limitations, a different style of tool or size of air motor is necessary.

What if we treated our electric systems the same way we treat compressed air?

1. We would have to remove all the nameplates from the motors and electrical devices. We normally have no idea what volume or pressure is required of air using devices other than by trial and error.

2. We would buy electrical-using equipment with no regard to voltage, amperage, or the effect that it might have on the system, assuming that the local utility would compensate for whatever the results were on the system.

3. We would remove all the circuit breakers, transformers, capacitors, and starters from the system and use only primary power, regardless of need. If a particular user required control, we would put rheostats on those applications and nothing on the balance of applications.

4. We would use one or two sizes of wire and connection components on all electrical applications, regardless of voltage or amperage, and expect maintenance and the local utility to correct the system to compensate for how the production works. The size and selection of those components would be determined by the stores department and purchased based on price, availability, and minimizing inventory. Example: Use 1⁄4-in. hose and fittings on all applications regardless of flow or pressure. Once the connections are made, if the application doesn’t work, you simply increase the pressure supplied to the equipment until it works the way we want it to. Wouldn’t that be interesting to do with electricity?

5. Give every operator and supervisor the phone number of the local utility. If the equipment in production isn’t working the way that they want it to — regardless of any changes in speeds, feeds, faults, or any other problem — they simply call the local utility, who will alter the way they are supplying electricity to the plant to correct that single problem. If they cannot correct the problem with more whatever, they will simply buy more whatever or build another power plant and try again to solve the problem which was reported over the telephone. After all . . . electricity is free! Well . . . certainly compressed air is free . . . isn’t it?

Some of you may think that this example is ridiculous. Actually it would be a relatively close parallel to the way that most compressed air systems are operated. The sad part of this is that there are limited resources available to learn more about compressed air.

This article is based on Compressed Air System Solution Series, a book by R. Scot Foss, president, Plant Air Technology, Charlotte, N.C.